[r3n]

It seems to me that you expect:

1. You should not fail at anything.

2. You should not feel unfamiliar at anything.

3. It is your faults that you could not provide best answer for your clients.

But I think you will agree these ideas are unrealistic.

You will find out things that you know nothing about, and that is fine. Maybe next time when you are in the situation where you have to deal with uncertainty, just admit that you will not have the best answer, but you will have a good enough answer that is based on your experience and knowledge.

Book suggestions:

1. Feeling Good: The New Mood Therapy

2. How to Stop Worrying and Start Living

Both books teach me how to recognize those unrealistic standards I set for myself. I think they can help you too.